Sunday I am going to do my first 20 gallon day. Brewing 2 10 gallon batches back to back. Anything I should know now to help it go smoother. I'm planning on starting the second mash, during the first boil and not changing much else. Can anyone out there think of something they wish they'd known before they did their first double?

Two weeks ago, I did another back to back. I’m doing most of my six gallon brewing that way these days, it seems to be more fun that way. Previous experience with back to backs prompted these precautions:

1) Clean and sanitize your fermenters before brew day. Leave a little sanitizer in each one and airlock it, if you don’t do that already.

2) Let the person you share toothpaste with know that you’ll be running a big load of dishes around dinner time on your brew day.

3) Go shopping the night before for sandwich fixings and be sure you have enough coffee/coke. Before you go to bed, separate within individual plastic bags each addition, and place all your ingredients into an A batch and B batch box.

4) Print up your blank brew notes the night before and fill out all the steps you will do that day, yeast name, target OG, hops additions, time, etc. During the brew, cross off each step with a brightly colored pen. (Once you’re done with your first brew, fill in the rest—no, at the end of the day you won’t remember the exact OG or pitch temperature of your first batch, you’ll just remember being happy with them).

5) Eat a big breakfast and decide whether you’re really up to it. There’s no shame in stepping up one of your starters for next weekend. I tend to pull off 2 in 3 double days. Life happens.

6) Mash-in as early as possible (5.00am for me).

7) Do your easiest brew first. I tend to find that the first brew gets the cobwebs out and alerts me to the myriad small things that cause trouble. I find the second brew easiest. This is a highly debatable proposition.

8) Don’t RDWAHAHB during the first batch. Terrible things will happen.

9) Wash ASAP. If it’s not lunchtime, and you’re not doing anything, chances are you can wash something. Use two pasta pots to heat and pre-mix a little PBW to clean your mash vessel.

11) You’ll be testing your ventilation system to the limit. If, during the second brew you find your coffee/coke is really going to your head, quickly go outside. This happened to me, and scared some sense into me on my first back to back. I now use two box fans whenever I brew.

12) I like to decant my second starter, and then fill it with the first 12 or so oz, from my first batch. This gives me the option of brewing the second batch, or stepping up my starter. It also gives my double day brews a sorta kinship.

13) Once your wort is in the fermenter, airlock it. You’ll have plenty of time during the next mash to pitch and O2.

14) Clean your sanitary items, and leave the rest for Sunday afternoon. The delayed clean up of non-sanitary items allows plenty of time for silent gloating to oneself—“Damn, I really nailed it, they’re both going nuts….”

15) Like everything else in brewing, once you’ve done it a couple times, it’s no big deal. These are the highlights of my process (yeah, yeah, I know you’d hate to see the long version). Others will disagree, and once you find your own, I’m sure you will too. Good luck!

I so totally agree with most of Trog's points. I'll expand on a couple:

#2 -- Make sure you and your SO and your kids are on the same page about the whole thing. The last thing you need when you are tired and sweaty and starting to lose concentration is "You're not done YET? Well, how much longer?" and "Daddy! You said you'd play D&D with me!" every 15 minutes. Pre-allocate plenty of buffer time with everyone else in the house.

#3 -- Even if you don't weigh and tag everything the night before, do it before you mash in the first batch. That means everything. Put the Whirlfloc tablet in with the flavor hops and the measured brewing salts in with the grains. When I do a double, I will mash the second while boiling the first. That's just a little more than my brain can handle unaided. It's too easy to forget things.

#5 -- Do it. I used to think, "I just want to get started now. I'll grab something later." But I would lose track and not realize I was hungry until I was losing concentration. Breakfast is important prep work. Make time for it.

I'll add one more suggestion: Get one of those 3-way digital kitchen timers so you can be timing 3 different things. I got mine in the gadgets section at Stop & Shop. Don't rely on the wall clock when you are doing several things at once. (And write down what each timer is timing!)

Good luck. Double brew days are certainly more efficient than 2 singles. They just take more prep."Vime's approach to paperwork was not to touch it until someone was shouting, and then at least there would be someone to help him sort through the stacks." -- Terry Pratchett

Wow, I didn't think it would be that much more stressful. If a single batch takes me about 5-6 hours, how long will a double possibly take me. I was thinking that it would only take another 2 or so hours. Thanks for the input.

Well, I have a 2 kettles, 2 MTs and an extra burner and do double batches quite frequently. I guess that makes life a whole lot easier. I do almost none of the things mentioned above. I crush the grains the night before and have the recipes in hand, but thats about it. Eat breakfast after firing up the HLT. Always find time to squeeze in lunch. Takes about 1-2 extra hours. The good thing about double-batch days are: 1) more beer; and 2) single batch days are a walk in the park.

There were like 20 suggestions and none of them were "check how much propane you have". When you're doing 20 gallons you need the second propane tank, the one that is normally the backup. So as the I ran out on the first I realized my mistake. My wife saved the day and went and got it filled for me so I think It only added about 45 minutes. So I did 20 gallons in about 7.5 hours. The only other concern I have was since I was a little late mashing in the second batch it coincided with the chilling of the first batch adn the two kegs were right next to each other. I am sure some grain dust made it the 12 inches or so to the BK. Isn't grain dust bad for unfermented wort? I pitched a big jar of 2007 slurry so hopefully all will be well.

I was going to brew last weekend until I realized I didn't have ANY LP. Even the gas grill was empty. That's not the first time that has happened so I've been debating about checking how much it would cost to have natural run out to the garage. I'm assuming it's probably still not worth it.

I did my first back to back brews in one day on Saturday and was so pumped up I did another on Sunday morning. Now I have to scramble to find something to brew in next week. Ah well, I might just have to drink.

A second burner and a second set of hands can help you overlap batches and trim an hour plus off the total time.

Having everything set the night before is invaluable. My goal is to have my first tasks set up as follows 1) pour coffee, 2) light burner. All of this presumes that all the gear is set up, grain milled, starters bubbling days ahead of time, water filtered, carboys scrubbed and ready.

I'll add my voice to the family/marital advice: don't promise what you can't deliver. Add an hour onto what you anticipate. I recommend doing a double on a weekday off, not a weekend.